A functional homolog of Escherichia coli NhaR in Vibrio cholerae.
Escherichia coli NhaR controls expression of a sodium/proton (Na+/H+) antiporter, NhaA. The Vibrio cholerae NhaR protein shows over 60% identity to those of Escherichia coli and Salmonella enteritidis. V. cholerae NhaR complements an E. coli nhaR mutant for growth in 100 mM LiCl-33 mM NaCl, pH 7.6, and enhances the Na+-dependent induction of an E. coli chromosomal nhaA::lacZ fusion. These findings indicate functional homology to E. coli NhaR. Two V. cholerae nhaR mutants were constructed by using kanamycin resistance cartridge insertion at different sites to disrupt the gene. Both mutants showed sensitivity to growth in 120 mM LiCl, pH 9.2, compared with the wild-type strain and could be complemented by the introduction of V. cholerae nhaR on a low-copy-number plasmid. An nhaR mutation had no detectable effect on the virulence of the V. cholerae strain in the infant mouse model, suggesting that the antiporter system involved is not required in vivo, at least in this animal model.
Williams
S G
SG
Department of Microbiology and Immunology, University of Adelaide, South Australia, Australia. swilliam@microb.adelaide.edu.au
Carmel-Harel
O
O
Manning
P A
PA
D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D004268:DNA-Binding Proteins; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism*; D029968:Escherichia coli Proteins; D018021:Lithium Chloride / Q000494:pharmacology; D008969:Molecular Sequence Data; D016296:Mutagenesis; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis / Q000235:genetics; D012477:Salmonella enteritidis / Q000235:genetics; D017386:Sequence Homology, Amino Acid; D017923:Sodium-Hydrogen Exchangers / Q000096:biosynthesis / Q000235:genetics; D014157:Transcription Factors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D014734:Vibrio cholerae / Q000187:drug effects / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*
D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; C102839:NhaA protein, E coli; D011993:Recombinant Fusion Proteins; D017923:Sodium-Hydrogen Exchangers; D014157:Transcription Factors; C074687:nhaR protein, E coli; D018021:Lithium Chloride